1. Field of the Invention
The present invention relates to an apparatus for interrupting the flow of current in a cable that extends from the battery in a motor vehicle to a consumer that is also located in the vehicle, such as a starter, an engine, or the like.
It is important, for reasons of safety, that the flow of current in an automobile from the battery to a consumer in the vehicle be interrupted in the event of an accident. This is particularly important with regard to the starter. The reason for this is that accident-caused damage to the current-carrying cables can cause short circuits, which in turn can cause fires and explosions.
German utility model DE-GM 84 33 042.2 discloses a device which comprises a housing, formed with a cylindrical recess, that has a first connection terminal and a cylindrical bolt with a second terminal; the bolt can be inserted into the recess and is retained therein by frictional engagement. The cable originating at the battery and the cable leading away to the consumers are connected to the two connection terminals. A charge in the form of a pyrotechnical element that can be tripped by a sensor, is also located in the housing.
In the event of an accident, the sensor outputs a pulse that ignites the charge. By the resultant gas pressure, the bolt located in the cylindrical recess is driven out of the recess, thereby breaking the existing electrical connection between the battery and the consumers.
However, this known device has the disadvantage that because of the frictional engagement of the two coupling parts, both a mechanical connection and an electrical connection is made. In order to assure both a good mechanical connection and a good electrical connection, the coupling parts associated with one another must match exactly, which means high production costs. There is also the danger that the two coupling parts, because of the vibration that occurs during the operation of the vehicle, will come apart. This either increases the junction resistance or completely breaks the electrical connection. By an increased flow of current, welding together of the two coupling parts can also happen, so that the operability of the device is no longer assured. Moreover, from deformations caused by mechanical factors, such as heat warping, the frictional engagement between the two coupling parts can also become so strong that the operability of the device is no longer assured.